Dynamic Energy Budget Theory

Dynamic Energy Budget Theory - ITnia Sousa with contributions from :Bas KooijmanWhat is metabolism?

A Theory of MetabolismWhat is metabolism?Using resources (energy and materials) to make new cells, to repair old ones, and to get rid of wastes requires the assemblage of biochemical pathways that we call metabolism. Metabolism is a universal feature of life that links organisms with their environment, and with each other.

A Theory of Metabolism

What is metabolism?Using resources (energy and materials) to make new cells, to repair old ones, and to get rid of wastes requires the assemblage of biochemical pathways that we call metabolism. Metabolism is a universal feature of life that links organisms with their environment, and with each other.What should a theory of metabolism look like?

A Theory of MetabolismWhat is metabolism?What should a theory of metabolism look like?It should be a qualitative and quantitative description of how organisms use mass and energy to do the things they need to do to stay alive

A Theory of MetabolismWhat is metabolism?What should a theory of metabolism look like?It should be a qualitative and quantitative description of how organisms use mass and energy to do the things they need to do to stay alive Which type of questions can a theory of metabolism help you with?

A Theory of MetabolismWhat is metabolism?What should a theory of metabolism look like?Which type of questions can a theory of metabolism help you with? Why do weak accids have an effect on the growth of yeasts?What is the minimum amount of food (and habitat) a panda needs to survive?If the temperature of ocean increases by 0.5C what will happen to the survival of the sardine larvae?

A Theory of Metabolism

ToxicologyWhich is the toxicity of the environmental concentration of a compound? Which are the toxic effects of a compound?Climate ChangeWill an increase in 1C have a drastic impact on the distribution range of a species?Waste water treatment plantWhat are the necessary conditions to mantain an healthy microbian comunity in the biological reactors?Fisheries ManagementWhat is the sustainable fishing quota?

Environmental ApplicationsMinamata is a small factory town facing the Shiranui Sea, and Minamata Bay is part of this sea. Chisso Corporation in Minimata which produced plastics, drugs, and perfumes released methylmercuryfrom 1932 to 1968 in the industrial wastewater whichbioaccumulatedin shellfish and fish in eaten by the local people.In the mid-1950's people begin to notice a "strange disease". Victimswere diagnosed as having a degeneration of their nervous systems. Minimata Disaster: Mercury Poisoning

It captures the quantitative aspects of metabolism at the individual level for all species

Why the hope for generality?universality of physics and evolutionEntropy production is >=0cell universality: cells are metabolically very similar, independently of the organism or its size widespread biological empirical patternsWhat is DEB theory?

Growth as a function of time

Depends on length at birth, maximum length and growth rateIt was proposed in 1929 by Putter and in 1938 by Von BertalanffyA widespread biological empirical fact: Von Bertalanffy growth

11A widespread biological empirical fact:Kleibers Law Metabolism (respiration or heat production) as a function of mass

Metabolism increases with weight raised to the power 3/4Max Kleiber originally formulated this basic relationship back in the 1930s.

What is the relationship between specific metabolism and weight?Relationship between specific metabolism and weight?A widespread biological empirical fact:Kleibers Law

Indirect calorimetry calculates heat that living organisms produce from their production of carbon dioxide and nitrogen waste and from their consumption of oxygen. Lavoisier noted in 1780 that heat production can be predicted from oxygen consumption this way, using multiple regression. A widespread biological empirical fact:Indirect Calorimetry

Consistency with other scientific knowledge (thermodynamics, evolution, etc)Consistency with empirical dataLife-cycle approach: embryo, juvenile and adult

Occams razor: the general model should be as simple as possible (and not more)Occams biological razor: organisms increased their control over metabolism during evolutionBasic Concepts in DEB Theory

The individual: time and spatial scalesBasic Concepts in DEB Theory

Metabolism in a DEB individual. The boundary of the organism Rectangles are state variablesA DEB organism mass descriptionME - ReserveMV - StructureMH - MaturityDraw the scheme in the blackboard. The frontiers and the state variables.17What defines a DEB organism?BiomassMv - Mass of Structure ME - Mass of Reserve Life-Cycle approach: different life stagesMH - Level of Maturity (it represents neither mass nor energy)

What about other possibles state variables such as age?

DEB model: the State Variables

These gouramis are from the same nest, they have the same age and lived in the same tankSocial interaction during feeding caused the huge size differenceAge-based models for growth are bound to fail; growth depends on food intakeWhy not age as a state variable? Trichopsis vittatus

Indices for compoundsIndices for transformationsGeneralNotation

Strong homeostasisReserve & structure have constant aggregated chemical compositionDEB model: Reserve and StructureStrong homeostasisReserve & structure have constant aggregated chemical compositionDEB model: Reserve and StructureWhy more than 1 state variable to define the biomass?The aggregated chemical composition of organisms is not constant it changes with the growth rate

Why not more than 2 state variables to define biomass?Two are sufficient (in animals and bacteria) to capture the change in aggregated chemical composition with the growth rateStrong homeostasis -> higher control over metabolism

What does a variable aggregated chemical composition implies?Metabolism at the chemical level is very complex

It is not possible to impose mass conservation without modeling all chemical reactions (which is impossible).Knowledge on motors of cars is of little help to solve queuing problems

Why not use thousands of chemical species and chemical reactions to define the organism?

Weak homeostasisAt constant food organisms tend to constant aggregated chemical compositionDEB model: Reserve and StructureEmpirical support: growing biomass tends to constant chemical composition at constant foodWeak homeostasis -> higher control over metabolism

What has to be the relationship between MV and ME to ensure a constant aggregated chemical composition? Life Stages (dark blue) and transitions (light blue)

Essential switch points for metabolic behaviorBirth (start of feeding)Puberty (start of allocation to reproduction)Switch points sometimes in reversed order (aphids)

DEB model: MaturityembryojuvenileadultfertilizationbirthpubertydeathweaningbabyinfantMHb- threshold of maturity at birthMHp- threshold of maturity at puberty

25Organisms have a number of life stages, each having its own metabolic repertoire.Most animals and plants have an embryo (maturation, but no feeding or reproduction), juvenile (maturation and feeding, but no reproduction) and adult (reproduction and feeding but no maturation).Endless variations on this basic scheme exist.Life-stages: Metamorphosis

26Ecdysozoa have to moult to increase in volume.The last moult in insects is not to increase in volume but to develop wings and prepare for reproduction.Insects have trachean tubes to transport gases (CO2, O2).The inner lining of these tubes is moulted as well (see the white threats), so these tubes cannot branch.

West, Brown & Enquist hypothesized (Nature 400 (1999): 664-668) that the reason for why respiration is proportional to weight to the power is to minimize transport costs in space-filling fractally branching networks, and mentioned trachean tubes as example.MHb - Extremes in relative maturity at birth

Ommatophoca rossii (Ross Seal) 1.7-2.1 m, 129-216 kg 1.3-2.2 m, 159-204 kgAt birth: 1 m, 16.5 kg; ab = 270 d

Didelphus marsupiales (Am opossum) , 0.5 + 0.5 m, 6.5 kgAt birth: